The present invention relates to diesel electric passenger locomotives and, more specifically, to simplification of diesel electric passenger locomotive auxiliary and hotel power systems while operating on third rail power.
In a typical passenger locomotive, it is standard to have three systems which need to be powered. One system is the traction motor powering system for providing power to each traction motor, usually provided on each axle; a second system is the passenger car or hotel loads, such as lighting, heating, and air-conditioning; and a third system is the locomotive auxiliary loads, such as blowers, compressors, battery charging, and excitation requirements. Typically, for a locomotive, these systems are powered by the diesel engine.
However, there are some situations when the diesel engine is required to be off and, therefore, not available for powering the locomotive systems. For example, emission requirements may require that the diesel be shut down in tunnels which are used to carry both subway and locomotive traffic. In such situations, where the transportation system is operating on two rails, it is common to use third rail power as the power delivery system. The third rail power is used to provide the same locomotive functions that are normally provided by the diesel engine. Hence, a locomotive traveling through a tunnel, with the diesel de-energized, is operating similar to a transit car, where the power delivery system is provided by an electrified third rail.
When third rail power is used to provide the locomotive diesel engine functions, a certain amount of equipment is added to the locomotive power system. For instance, traction power is supplied directly from the third rail source through a series of resistors and contactors, in order to provide variable voltage/power capability, and to the series DC traction motors. The starting resistors and contactors are supplied specifically for this purpose.
In addition, locomotive auxiliary power requirements and head end power are provided by the head end power system. Head end power is provided from the third rail by a motor alternator set. This set utilizes a compound wound DC motor driving a three phase alternator. Starting resistors and contactors are supplied to bring the set up to its operating speed. A power transfer switch is then used to provide power for excitation, which requires inclusion of a motor excitation panel; power to run the locomotive auxiliaries at a reduced speed, thereby requiring an additional circuit breaker, transformer, and power transfer switch; the power for locomotive battery charging and air conditioning; and enough power for the passenger cars that are attached to the locomotive.
Prior art methods for providing third rail power are inefficient for several reasons. First, this additional equipment adds significant weight to the locomotive. Furthermore, duplication of the locomotive auxiliary and hotel power controls can cause the locomotive itself to be larger, to accommodate the installation of the additional equipment. Finally, some equipment is not used at all during third rail operation, including the diesel engine, several exciter panels, normal locomotive battery charger, main alternator, auxiliary alternator, normal head end power alternator, and main propulsion rectifiers.
It is seen then that there exists a need for a means of providing a diesel passenger locomotive with a more efficient dual power producing capability.